A solution-processed ternary copper halide thin films for air-stable and deep-ultraviolet-sensitive photodetector

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Lead-halide perovskites show promise for photodetectors due to excellent optoelectronic properties.
• Instability and lead toxicity hinder practical applications of lead-halide perovskites.
• Existing photodetector research primarily focuses on visible and near-infrared regions, neglecting deep-ultraviolet (DUV) detection.

Purpose of the Study:

• To develop a stable, lead-free photodetector sensitive to the deep-ultraviolet (DUV) light region.
• To utilize solution-processed ternary copper halides Cs3Cu2I5 thin films as the light-absorbing material.
• To evaluate the photodetection performance and stability of the Cs3Cu2I5-based device.

Main Methods:

• Fabrication of a photoconductive detector using solution-processed Cs3Cu2I5 thin films.
• Characterization of the photodetector's sensitivity to different wavelengths, focusing on the DUV region (<320 nm).
• Assessment of photodetection performance metrics including photoresponsivity, specific detectivity, and response speed.
• Evaluation of the material's and device's stability under various conditions (heat, UV light, ambient air).

Main Results:

• The Cs3Cu2I5 photodetector exhibits high sensitivity to DUV light (<320 nm) and is unresponsive to visible light.
• Outstanding photodetection performance was achieved: photoresponsivity of ~17.8 A W−1, specific detectivity of 1.12 × 10^12 Jones, and fast response times (465/897 μs).
• The lead-free Cs3Cu2I5 material demonstrates remarkable stability against heat, UV, and ambient conditions, maintaining performance after 11 hours of continuous operation and 80 days of storage.

Conclusions:

• Non-toxic Cs3Cu2I5 is a promising material for developing stable and environmentally friendly DUV photodetectors.
• The developed photodetector overcomes the limitations of traditional lead-halide perovskites in terms of stability and toxicity.
• This work paves the way for future optoelectronic systems utilizing efficient and robust DUV detection capabilities.